The invention relates to odor or chemical or biological sensors, and more particularly to sensors for detecting or monitoring chemical or biochemical conditions, including those related to diseases.
Almost any entity can be defined by its chemical (chemical, electrochemical or biochemical) state. The identification of such a state can be inferred or diagnosed by various markers that characterize the state. Changes in the values of the markers or changes in the applicable markers represent a transition from one state to another. This applies to be both living and non-living entities or systems.
For example, the toxic leak of an electrical transformer is possibly characterized by the presence of PCB fluid outside the transformer. In this case, the leaking state is marked by the external presence of the PCB marker. The well-being of a human, which is on the other extreme of complexity, could also be defined by his/her chemical or more precisely by his/her biochemical state with its corresponding markers. When a particular disease, illness or injury occurs and progresses, the presence of particular markers and their values for each disease would represent the status and the progression of the condition. Thus monitoring of the markers corresponding to the disease is essential for medical diagnosis and treatment.
For traditional medical diagnosis, blood and urine and the two most common media for obtaining these markers for evaluation. However, a medium that has been largely neglected by the medical community is expired gases or odors from one's breath or from other parts of the body. Such a technique offers the potential of totally non-invasive evaluation and investigation, a significant advantage over urine and blood assay. However, it has not gained wide acceptance for a number of reasons. First, very sensitive detectors such as those based on gas chromatography are expensive. Second, the necessary odor or gaseous signatures from the volatile markers for each disease condition have not been identified. Finally, other complicating factors that need to be corrected, such as the impact from the environment and the variability from individual to individual, have not been vigorously pursued and solved. The invention described herein solves all these problems.
Applying this approach to “diagnosis” problems with equipment, the “health” of an electrical transformer can be similarly evaluated. For example, detection of PCB odor or vapor would signify that the transformer is not healthy since it is leaking a harmful substance. One can of course analyze the fluid itself for the presence of PCB, just like one can analyze markers in the blood and urine of a human body. However, the sniffing of the vapor or odor offers the advantage of “global” evaluation. If a detector is sensitive enough, it can “smell” the leaking transformer miles away, a feat that is impossible by fluid evaluation, since fluid can only be detected locally or on-site. Moreover, often more than one healthy transformer can be screened at one time at one location; whereas the local method of checking for leaking fluid has to be done item-by-item, posing potential health hazard, enormous inconvenience, and cost disadvantages. Furthermore, such odor or gas detection may be even more sensitive than PCB fluid detection, and allows the potential of uncovering developing leaks before the actual leaking of the toxic fluid itself.
The leak of the transformer depends internally on the transformer itself; for example, its construction can vary from transformer to transformer. Thus any device to be used to pick up the markers should be adaptive to the entity in order to be truly effective in evaluating the present state and/or predicting the future state of the entity. Such an adaptive system has to “learn” and accumulate “understanding” of each individual entity to do an effective job. In the case of a human being, this could be especially true. For example, if one uses pentane as a marker for lipid peroxidation and as an indirect marker for diabetic conditions within the body, one has to be aware of the possibility that pentane production and its metabolism might be different from one human being to another, even though both persons may have the same diabetic condition. In order not to misinterpret the marker, the system may have to be adaptive to each individual.
The environment surrounding an entity can have a strong impact on any diagnostic system because an entity usually does not exist by itself. It exists in an environment and thus could be linked or coupled with the environment. Thus the evaluation of the state and its progression are possibly determined not only internally by the entity but also by its existing environment. As an example, if normally the PCB odor exists even when there is no transformer leak because the transformer is located near a PCB contaminated site, then the detection or evaluation of the health of the transformer has to take into account the environmental PCB. Correction in this case may be simple, but corrections with complicated algorithms may be needed in the case of the human body because of the body's complexity. For example, pentane from the environment can be taken into the lung and come back out directly, or it can be absorbed into the tissues of the body and then desorb slowly. These pentane contributions from the lung and the tissue should not be misinterpreted as true internal production due to the intended assessment of the lipid peroxidation.